'\" te
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.TH LDAP_SORT 3LDAP "Jan 27, 2002"
.SH NAME
ldap_sort, ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp \- LDAP
entry sorting functions
.SH SYNOPSIS
.LP
.nf
cc[ \fIflag\fR... ] \fIfile\fR... -lldap[ \fIlibrary\fR... ]
#include <lber.h>
#include <ldap.h>

\fB\fR\fBldap_sort_entries\fR(\fBLDAP\fR \fI*ld\fR, \fBLDAPMessage\fR \fI**chain\fR, \fBchar\fR \fI*attr\fR,
     \fBint (\fR\fI*cmp\fR)());
.fi

.LP
.nf
\fB\fR\fBldap_sort_values\fR(\fBLDAP\fR \fI*ld\fR, \fBchar\fR \fI**vals\fR, \fBint (\fR\fI*cmp\fR)());
.fi

.LP
.nf
\fB\fR\fBldap_sort_strcasecmp\fR(\fBchar\fR \fI*a\fR, \fBchar\fR \fI*b\fR);
.fi

.SH DESCRIPTION
.sp
.LP
These functions are used to sort lists of entries and values retrieved from an
LDAP server. \fBldap_sort_entries()\fR is used to sort a chain of entries
retrieved from an LDAP search call either by DN or by some arbitrary attribute
in the entries.  It takes  \fIld\fR, the LDAP structure, which is only used for
error reporting,  \fIchain\fR, the list of entries as returned by
\fBldap_search_s\fR(3LDAP) or \fBldap_result\fR(3LDAP). \fIattr\fR is the
attribute to use as a key in the sort or NULL to sort by DN, and  \fIcmp\fR is
the comparison function to use when comparing values (or individual DN
components if sorting by DN). In this case,  \fIcmp\fR should be a function
taking two single values of the  \fIattr\fR to sort by, and returning a value
less than zero, equal to zero, or greater than zero, depending on whether the
first argument is less than, equal to, or greater than the second argument. The
convention is the same as used by \fBqsort\fR(3C), which is called to do the
actual sorting.
.sp
.LP
\fBldap_sort_values()\fR is used to sort an array of values from an entry, as
returned by \fBldap_get_values\fR(3LDAP). It takes the LDAP connection
structure  \fIld\fR, the array of values to sort  \fIvals\fR, and  \fIcmp\fR,
the comparison function to use during the sort. Note that  \fIcmp\fR will be
passed a pointer to each element in the \fIvals\fR array, so if you pass the
normal char ** for this parameter, \fIcmp\fR should take two char **'s as
arguments (that is, you cannot pass  \fIstrcasecmp\fR or its friends for
\fIcmp\fR). You can, however, pass the function \fBldap_sort_strcasecmp()\fR
for this purpose.
.sp
.LP
For example:
.sp
.in +2
.nf
	LDAP *ld;
	LDAPMessage *res;
	/* ... call to ldap_search_s(\|), fill in res, retrieve sn attr ... */

	/* now sort the entries on surname attribute */
	if ( ldap_sort_entries( ld, &res, "sn", ldap_sort_strcasecmp ) != 0 )
		ldap_perror( ld, "ldap_sort_entries" );
.fi
.in -2

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for a description of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving
.TE

.SH SEE ALSO
.sp
.LP
.BR qsort (3C),
.BR ldap (3LDAP),
.BR ldap_result (3LDAP),
.BR ldap_search (3LDAP),
.BR attributes (7)
.SH NOTES
.sp
.LP
The \fBldap_sort_entries()\fR function applies the comparison function to each
value of the attribute in the array as returned by a call to
\fBldap_get_values\fR(3LDAP), until a mismatch is found. This works fine for
single-valued attributes, but may produce unexpected results for multi-valued
attributes. When sorting by DN, the comparison function is applied to an
exploded version of the DN, without types. The return values for all of these
functions are declared in the <\fBldap.h\fR> header file.  Some functions may
allocate memory which must be freed by the calling application.
